Agricultural product delivery systems are known to utilize various mechanisms, including mechanical and/or pneumatic systems, i.e., a flow of air, to assist in the delivery and movement of particulate material or product such as fertilizer, seed, insecticide or herbicide from a product supply chamber through an interior passage provided by a series of elongate tubes which extend from the product supply chamber to a product applicator that places the product on or in growing medium, such as soil. Such agricultural product delivery systems are commonly employed in planters, air drills, fertilizer and pesticide applicators and a variety of other agricultural implements.
Agricultural implements that employ an agricultural product delivery system are known to have a particulate material supply source such as one or more tanks that are loaded with the particulate material or materials to be applied. The tanks have or are associated with a metering device, which typically consists of a rotating element, which meters the particulate materials from the tanks into a set of distribution channels, such as conduits, hoses, etc., for application to the farm field. In most systems, a pneumatic source such as a fan or blower provides air to convey and distribute material through the distribution channels. Once the metering of particulates is done and the mix of air and particulates is in the distribution channels, the solid concentration should remain nearly constant and in dilute phase.
Systems as described have provided certain advantages and have worked acceptably in some aspects, but are not without disadvantages, inefficiencies or inconveniences. For example, it is desirable to use a material supply source, such as a tank, with different applicator equipment by, for example, coupling the tanks with a planter for planting seed, and later coupling the same tank equipment with an applicator for applying needed pesticides and/or fertilizer.
However, with pneumatic conveying or delivery systems, the pressure drop across various portions of the delivery system can often result in different rates of the particulate material being dispensed from different supply lines and associated nozzles. It is often difficult to equalize airflow between parallel supply lines fed by the same air flow source, or fan as the supply lines may have different air flow resistances caused for various reasons within the supply lines. As a result, the air flow is often directed to the supply line with the least resistance, i.e., preferential flow, when the metering devices for the supply lines cease injecting particles into the supply lines, such as for sectional control, or injecting particles at a reduced rate, such as for turning compensation. Alternatively, as a result of its position or configuration, the air flow source/fan may simply direct air flow primarily towards one side of the conveying system.
What is needed in the art is a pneumatic agricultural product conveying system which improves efficiency and convenience of the applicator without further complicating its construction and that provides a more even distribution of the air flow from the air flow source across all supply lines and nozzles of the system.